The Treatment of Cancer

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PrecisThis article begins with a brief explanation of the medical assessment that newly-diagnosed patients undergo to evaluate their cancer. It also provides information about various treatments that doctors administer to cancer patients. A number of complex scientific terms (identified in bold type) are explained in the text.

Staging of Cancer

Once a diagnosis of cancer is made, it is important that the stage of disease be assessed. Stage generally refers to the degree to which the cancer has spread beyond its original location. Lower stages of cancer (stages I and II) are generally more confined to their site or region of origin than more advanced stages (III or IV).

Different cancer types are staged in different ways, according to a complex series of rules. While there are subtle differences in the staging rules for different cancer types, a physician generally needs to look at three things:

"T" stage (tumor stage), defined according to the size of the tumor itself;

"N" stage (nodal stage), defined according to the number of lymph nodes which contain cancer; and

"M" stage (stage of metastatic disease), defined according to the presence (or absence) of cancer that has spread into other organs or parts of the body.

The T, N, and M stages have many nuances within them, and each is subdivided (T1, T2, T3, etc.) Different combinations of T, N, and M combine under the staging rules to determine whether a patient is stage I, II, III, or IV. In some cancers, there are even additional stages to account for unique situations (Stage V, for instance). It should also be noted that some cancers are staged with different staging systems, but the TNM system is the most common.

Ultimately, the goal of staging is threefold:

To help select the most appropriate therapy for the patient;

To help predict a patient's prognosis; and

To help future patients by assessing your response to therapy and tracking that along with the treatment responses of others with the same stage of cancer. This is necessary so that physicians can determine which treatments work best for which patients, so that less effective treatments can be discarded.

A patient's cancer stage is evaluated in a variety of ways. These include taking a thorough history of the patient's disease, doing a careful physical examination, and obtaining laboratory and radiographic studies (various blood tests, a chest x-ray, and abdominal CT scan, etc.) In some cases, surgical exploration is required to fully stage a patient's disease. In other cases, surgeons need to extract only a small sample of the cancerous tissue (a biopsy), which is generally a relatively minor procedure.

Staging, while important for most cancers, does not tell the whole story. Other factors such as tumor biology, the patient's overall medical condition, and the skills and resources available to the health care team can all impact on the ultimate outcome.

Cancer Grade

As mentioned in Part I of this article, cancerous cells can be "graded" according to their degree of "differentiation". Differentiation refers to how closely the cancerous cells resemble their cells of origin. The more differentiated a cancer cell looks, the closer it resembles cells belonging to its organ of origin. The more undifferentiated a cell is, the less "normal" it looks under a microscope. A differentiated colon cancer, for example, is cancerous, but it still looks, under the microscope, like "colon" cells. It may also behave as a colon cell (more or less) in terms of attachment to its neighboring cells. In some cancers, grade can affect the cancer stage and/or impact on treatment decisions (more about this in a moment).

Assessment of tumor type and grade is made by a pathologist. Pathologists are physicians
trained in looking at tumor samples both as a whole and under the microscope to assess their type, grade and other features such as invasiveness and lymphatic involvement.

Cancer Treatment

The treatment of cancer is a very complex subject. The following discussion is quite general, and not all parts of it apply to all types of cancer. For that reason, patients are urged to consult OncoLink's Cancer Types section for more
specifics as to how the following might apply to them.

Surgery
Surgery is often the first step in the treatment of cancer. The objective of surgery varies. Sometimes it is used to remove as much of the evident tumor as possible, or at least to "debulk" it (remove the major bulk(s) of tumor so that there is less that needs to be treated by other means). Depending on the cancer type and location, surgery may also provide some symptomatic relief to the patient. For instance, if a surgeon can remove a large portion of an expanding brain tumor, the pressure inside the skull will decrease, leading to improvement in the patient's symptoms.

Not all tumors are amenable to surgery. Some may be located in parts of the body that make them impossible to completely remove. Examples of these would be tumors in the brainstem (a part of
the brain that controls breathing) or a tumor which has grown in and around a major blood vessel. In these cases, the role of surgery is limited due to the high risk associated with tumor removal.

In some cases, surgery is not used to debulk tumor because it is simply not necessary. An example is Hodgkin's Lymphoma, a cancer of the lymph nodes that responds very well to combinations of chemotherapy and radiation therapy. In Hodgkin's Lymphoma, surgery is rarely needed to achieve cure, but almost always used to establish a diagnosis.

Chemotherapy
Chemotherapy is another common form of cancer treatment. Essentially,
it involves the use of medications (usually given by mouth or
injection) which specifically attack rapidly-dividing cells (such as
those found in a tumor) throughout the body. This makes chemotherapy
useful in treating cancers that have already metastasized, as well as
tumors that have a high chance of spreading through the blood system
but are not evident beyond the primary tumor. Chemotherapy may also
be used to enhance the response of localized tumors to surgery and
radiation therapy. This is the case, for example, for some cancers of
the head and neck.

Unfortunately, other cells in the human body
which also normally divide rapidly (such as the lining of the stomach
and hair) are also affected by chemotherapy. For this reason, some
(though not all) chemotherapy agents induce nausea or hair loss.
These side effects are temporary, and doctors have medications they
can provide to help alleviate many of these side effects. So, in
general, chemotherapy treatments are well tolerated by patients. As
our knowledge of science has continued to grow, researchers have
devised newer chemotherapeutic agents that are not only better at
killing cancer cells, but that also have fewer side effects for the
patient. Often, a patient's fear of chemotherapy treatment is worse
than the reality. For more information about the side effects of
cancer treatment, see OncoLink's Coping with Side Effects section.

Chemotherapy is administered to patients in a variety of ways. Some
are pills that are taken daily or once a week or some other schedule.
Some are administered by an intravenous injection. For those, a
patient goes to the doctor's office and spends several hours there
while the medication is administered, or perhaps spends a day or night
in the hospital. Some other chemotherapeutic agents require
continuous infusion into the bloodstream, 24 hours a day. For those,
a minor surgical procedure is performed to implant a small pump that
the patient wears. This pump then slowly administers the
medication. In many cases, a permanent port is placed in a patient's
vein so that they do not have to have repeated needle sticks.

Chemotherapy treatment often involves the use of more than one
medicine at a time. There are many different chemotherapy
combinations, each used for different types and stages of cancers.
These combinations often have acronyms which are derived from the
first letter of each of the chemotherapy agents in the combination.
For this reason, a patient may hear a physician refer to "MOPP
chemotherapy" (nitrogen Mustard, Oncovin, Procarbazine and Prednisone)
or some other acronym. Depending on the combination of agents in the
therapy, a patient may have some combination of pills or intravenous
injections to undergo, administered according to a particular
schedule.

Chemotherapy schedules also involve a "break" or "vacation" to allow
the body to recuperate. The exact timing of this break depends on the
type of cancer and the chemotherapy combination being used, as well as
a patient's response and tolerance. But, a hypothetical example might
include receiving chemotherapy for three weeks in a row and then
having a week off, then restarting again for three weeks, then a week
off, and so on. A patient might undergo these "cycles" four or six
times. (The exact number of cycles, too, depends on the regimen, the
cancer type, and sometimes the patients response and tolerance).

Radiation Therapy
Radiation therapy is another
commonly-used weapon in the fight against cancer. Radiation kills
cancer by damaging the DNA within the tumor cells. The radiation is
"applied" two possible ways. The first, and most common, involves
pointing a beam of radiation at the patient in a highly precise
manner, focusing on the tumor. To do this, a patient lies on a table
and the beam moves around him/her. This only takes a couple minutes,
but is done five days per week for 3-6 weeks (depending on the type of
tumor), to achieve a particular total prescribed "dose."

Another radiation method sometimes employed, called
brachytherapy, involves taking
radioactive pellets ("seeds") or wires and implanting them in the body
in the area of the tumor. Sometimes these implants are temporary, and
sometimes they are permanent. In the case of permanent implants, the
radiation in the seeds "decay" or fade away over a period of days or
weeks so that the patient is not radioactive. For temporary implants,
the entire dose of radiation is usually delivered in about two days,
and the patient must remain in the hospital during that time. After
the seeds or wires have been in place for the prescribed number of
hours, the radiation oncologist removes them and the patient can go
home.

In either case, radiation is generally delivered to a very targeted
area, to gain local control over a cancer (as opposed to treating the
whole body, as chemotherapy does.)

Bone Marrow Transplantation
Some highly selected patients may be referred for bone marrow
transplants. This procedure is usually performed either because a
patient has a cancer that is particularly aggressive or because they
have a cancer that has relapsed after being treated with conventional
therapy. Bone marrow transplantation is a complicated procedure.
There there are many types, and they vary in their potential for
causing side effects and cure. Most transplants are performed at
special centers, and in many cases their use is considered
investigational.

In preparation for a transplant, a patient is treated with high doses
of chemotherapy and/or radiation (usually to the whole body). This
preparatory therapy is designed to destroy cancerous cells in the bone
marrow and other areas of the body. In some cases, it is also
designed to suppress the body's immune system so that the new donated
marrow is less likely to be "rejected" [Some transplants use marrow
that is collected in advance from the actual cancer patient. These
transplants are not associated with the rejection risk.]. After
preparation is complete, the patient receives a transplant of donated
bone marrow infused by vein. The marrow may come from a
specially-matched donor (allogeneic transplant) or may be the marrow
the patient previously donated (an autologous transplant). As a side
effect, the preparatory regimen may also injure healthy constituents
of a patient's marrow and other tissues such as the gut. Throughout
this process, the patient remains in the hospital in an "isolation"
room, this because the patient's immune system is severely compromised
until the transplanted bone marrow "takes" and the patient's blood
counts rise to a sufficient level. Other organs that are injured
during the transplant recover in much the same way that the marrow
does. The patient is discharged when after sufficient marrow and
organ recovery.

Other Therapies
There are a number of other therapies, though most of them are still
being explored in clinical trials and have not yet become standard of
care. Examples include:

Immunotherapy - There are
various techniques employed, but the basic
point is to help the patient's own immune system fight the cancer,
quite separately from radiation or chemotherapy. Oftentimes, to
achieve the goal, researchers inject the patient with a
specially-derived vaccine. The most research in this area has been
conducted on melanoma, though other cancers are also now being
targeted.

Monoclonal Antibodies - These
are small proteins that are especially designed to attach to cancerous
cells (and not normal cells) by taking advantage of differences in the
outer surface of the cancerous cell's membrane, as compared with
non-cancerous cells. Before administering the antibodies to the
patient, they are "tagged" (attached) to various compounds or are made
radioactive, such that the treatment better targets the cancerous
cells.

Anti-Angiogenesis Factors - As
cancer cells rapidly divide and tumors grow, they can soon outgrow
their blood supply. To compensate for this, some tumors secrete a
compound which has been shown to help induce the growth of blood
vessels in their vicinity, thus assuring the cancer cells a continuous
supply of nutrients. Recently, researchers have been studying ways to
turn this process off (stopping the growth of blood vessels), with at least some success.

For more information about all these types of therapies, as well as
others, consult
OncoLink's Treatment Section. Readers should also understand that not every
experimental treatment modality is applicable to one particular kind
of cancer. Patients should therefore read the relevant Cancer Type about their cancer.

Clinical Trials
In addition, patients should look at various clinical trials that are currently
available. A clinical trial is a study designed to analyze the
utility of a new treatment. There are several types of clinical
trials including ones which study cancer treatment, cancer screening
and prevention, quality of life and others. Cancer treatment clinical
trials are categorized by Phases outlined below.

PHASE

OBJECTIVE

Phase I

Identifies safe dose level of a new drug or
treatment.

Phase II

Identifies the degree of response a
particular cancer shows to a new therapy.

Phase III

Compares the new treatment with standard
therapy.

A Phase III clinical trial is one of the most commonly offered to
cancer patients. In this type of clinical trial, patients may be
randomly assigned to a particular therapeutic regimen that is among
two or more possible treatments for a particular disease. One of the
possible treatments includes the "standard" or "traditional" therapy, and the other treatment regimens are considered "experimental".
Sometimes these studies are double-blinded, which means that neither
the patients nor the physicians know which particular treatment is
being administered. There are two reasons for blinding a study.
First, it is well known that patients who are aware they are receiving
an experimental therapy have a tendency to claim improvement in
symptoms (the "placebo effect") whether they are really improving or
not. Secondly, researchers who may be biased about a new therapy one
way or another, may unconsciously apply this bias to observed results
and thereby tarnish the outcome of the experiment. Double-blinding a
study controls for both of these possibilities.

Participation in clinical trials may be offered at no additional cost
to the patient compared to receiving standard treatments. Some
insurance companies reimburse for these experimental treatments. By
participating in the clinical trial process, patients themselves may
receive cutting-edge care and also contribute to medical knowledge,
thereby helping to improve treatment for future patients. The
University of Pennsylvania has many open Clinical Trials.